A collection of middlewares for the Wretch library.
Prerequisite: install Wretch
npm i wretch-middlewares<!-- Global variable name : window.wretchMiddlewares -->
<script src="https://unpkg.com/wretch-middlewares"></script>| Dedupe | Retry | Throttling cache | Delay |
|---|
Prevents having multiple identical requests on the fly at the same time.
- skip :
(url, opts) => boolean
If skip returns true, then the dedupe check is skipped.
- key :
(url, opts) => string
Returns a key that is used to identify the request.
import wretch from 'wretch'
import { dedupe } from 'wretch-middlewares'
wretch().middlewares([
dedupe({
/* Options - defaults below */
skip: (url, opts) => opts.skipDedupe || opts.method !== 'GET',
key: (url, opts) => opts.method + '@' + url
})
])./* ... */Retries a request multiple times in case of an error (or until a custom condition is true).
- delayTimer :
milliseconds
The timer between each attempt.
- delayRamp :
(delay, nbOfAttempts) => milliseconds
The custom function that is used to calculate the actual delay based on the the timer & the number of attemps.
- maxAttempts :
number
The maximum number of retries before resolving the promise with the last error. Specifying 0 means infinite retries.
- until :
(fetchResponse, error) => boolean | Promise<boolean>
The request will be retried until that condition is satisfied.
- onRetry :
({ response, error, url, options }) => { url?, options? } || Promise<{url?, options?}>
Callback that will get executed before retrying the request. If this function returns an object having url and/or options properties, they will override existing values in the retried request. If it returns a Promise, it will be awaited before retrying the request.
- retryOnNetworkError :
boolean
If true, will retry the request if a network error was thrown. Will also provide an 'error' argument to the onRetry and until methods.
import wretch from 'wretch'
import { retry } from 'wretch-middlewares'
wretch().middlewares([
retry({
/* Options - defaults below */
delayTimer: 500,
delayRamp: (delay, nbOfAttempts) => delay * nbOfAttempts
maxAttempts: 10,
until: (response, error) => response && response.ok,
onRetry: null,
retryOnNetworkError: false
})
])./* ... */
// You can also return a Promise, which is useful if you want to inspect the body:
wretch().middlewares([
retry({
until: response =>
response.json().then(body =>
body.field === 'something'
)
})
])A throttling cache which stores and serves server responses for a certain amount of time.
- throttle :
milliseconds
The response will be stored for this amount of time before being deleted from the cache.
- skip :
(url, opts) => boolean
If skip returns true, then the dedupe check is skipped.
- key :
(url, opts) => string
Returns a key that is used to identify the request.
- clear
(url, opts) => boolean
Clears the cache if true.
- invalidate
(url, opts) => string | RegExp | Array<string | RegExp> | null
Removes url(s) matching the string or RegExp from the cache. Can use an array to invalidate multiple values.
- condition
response => boolean
If false then the response will not be added to the cache.
- flagResponseOnCacheHit
string
If set, a Response returned from the cache whill be flagged with a property name equal to this option.
import wretch from 'wretch'
import { throttlingCache } from 'wretch-middlewares'
wretch().middlewares([
throttlingCache({
/* Options - defaults below */
throttle: 1000,
skip: opts.skipCache || opts.method !== 'GET',
key: (url, opts) => opts.method + '@' + url,
clear: (url, opts) => false,
invalidate: (url, opts) => null,
condition: response => response.ok,
flagResponseOnCacheHit: '__cached'
})
])./* ... */Delays the request by a specific amount of time.
- time :
milliseconds
The request will be delayed by that amount of time.
import wretch from 'wretch'
import { delay } from 'wretch-middlewares'
wretch().middlewares([
delay(1000)
])./* ... */